A different tone circuit

Ok, so the standard tone control is treble cut right? It bleeds the high frequencies through the capacitor off to ground. I've got a bass (my first DIY bass) that is really bottom heavy and I've been trying to figure out how to fix this.

I found an alternate tone diagram via a google search a while back and then lost it. I think I've recreated the general idea here.

I'm not 100% sure what you're trying to do.
Your sound with tone control on 'full' really has zero (or minimum) cut being applied. If that sound is too bassy, changing the cap value won't help you IMO.
What sort of strings are you using? If you're using nickels for example, try steels. What is the pickup in the bass in the bass also?

Unless I am high, and I haven't done anything to make that happen in 15 years, there IS a way to have a bass rolloff that works similar to the trble rolloff of a typical tone control. Look at GL basses. Passive B&T cut controls. How they do it, dunno. Works well too. I have a Tribby 2500. I'd open it up and take a look, but there are just too damn many wires in there. Scares a fella...

Unless I am high, and I haven't done anything to make that happen in 15 years, there IS a way to have a bass rolloff that works similar to the trble rolloff of a typical tone control. Look at GL basses. Passive B&T cut controls. How they do it, dunno. Works well too. I have a Tribby 2500. I'd open it up and take a look, but there are just too damn many wires in there. Scares a fella...

Lee

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Yes...you can also use (in a different schematic application) a LARGE size/value capacitor to act as a High Pass Filter where you would tailor the value to rolloff the unwanted low end frequencies. This would be a fixed frequency rolloff. However, for what you would pay for new pickups and also having to Guess what they would sound like, you can buy an on-board preamp and have all kinds of flexibility over tone control.

There are a number of ways to approach your situation. This suggestion is just one possibility.

Attached Files:

Thanks for all the tips. A few folks seem to think I'm just looking to change the cap value to get more treble. I'm actually proposing a different kind of tone circuit.

My idea is that the cap would serve as a high pass filter letting only the higher frequencies through to one side of the pot. The original (very bassy) signal gets routed to the other terminal of the pot. The pot then serves as a means to blend between the original very bass heavy signal and a higher signal that has been filtered by the capacitor.

Does that make any sense?

Seanm, that looks like a volume control with a high pass filter on it to me.

What is a Fender TBX tone control and how does it work?
Some Fender guitars come equipped with a special pot called
a TBX Tone Control T (treble) B (bass) X (Cut) that cuts
either treble or bass instead of a tone pot that cuts treble
frequencies only. This is done with a ganged 500K-1M ohm
control pot that is wired to work as a low-pass filter in one
direction and a high-pass filter in the opposite direction. A
center detent in the middle position is provided for the off
or "flat" position. Although Fender altered their Strat tone
configuration to have the TBX control the middle and bridge
pickups, it can be also be wired as a master treble/bass
control. The TBX can also be used in place of any standard
tone control on any guitar.

The TBX control is sort of what I'm after although I'd never use the treble cut side. From looking at the diagram, one side looks like a standard tone control. The other side is basically a tone control using a resistor instead of a capacitor. I'm not educated enough to figure out why this works.

the only time I've really jacked with caps, I had a pair of Bart M34C's in a bass with a Bart 3 band (I think both a TCT and NTMB). The pups were so dark they were useless. For whatever reason I ended up running a passive setup using a '54 Les Paul harness as the basis with two very different cap values on each tone pot, and a switching that ran both inside coils/both ouside coils/and both pups HB. The bass brightened up significantly all around, was all humbucking so dead quiet, and had an amazing array of useful tone options. The preamps did nothing but boost or cut what the pups put out - which was DARK!

Don't understand electronics but from what I can gather a resistor and capicitor fulfill two different functions. A resistor is designed to maintain a relatively fixed resistance whereas a capacitor is actually a storeage device. To my knowledge they definetly aren't used interchageably in guitar electronics. Aside of on PCB's about the only place I've seen resistors is on mid switches.

Ok, I tried this idea out today. Adjusting the pot had absolutely no effect on the sound. I tried taking the pot out of the circuit entirely and connected the hot wire from my pickup directly to one lead of the capacitor, the other capacitor lead I connected to the tip for the jack.

I expected the capacitor to work like a high pass filter. It did not. There was no difference in the sound with the capacitor or without it.

Ok, I tried this idea out today. Adjusting the pot had absolutely no effect on the sound. I tried taking the pot out of the circuit entirely and connected the hot wire from my pickup directly to one lead of the capacitor, the other capacitor lead I connected to the tip for the jack.

I expected the capacitor to work like a high pass filter. It did not. There was no difference in the sound with the capacitor or without it.

Anyone have any idea why?

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FWIW:

the first thing that comes to mind is that to A/B anything you really need to be able to do them side by side. In my experience, even the time it takes to flip a switch or swap basses can have an adverse affect and the more time lapse the less valid the A/B is.

From what I can gather you, you soldered it up with and without the cap and that's really way too much delay for any kind of A/B. That may be of use for a variation that is dramatic but not one that may be significant (one difficult to distinguish yet matters).

The second thing that comes to mind is that once the capacitor is at maximum storeage, with a steady current it simply functions as a direct circuit.

...The second thing that comes to mind is that once the capacitor is at maximum storeage, with a steady current it simply functions as a direct circuit.

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I think you must be right about this. I thought maybe the cap was bad, but I tried three different caps and then hooked it up as a traditional tone control and could definitely hear the difference.

As far as switching back and forth, everything was connected with alligator clips so this was pretty quick and there clearly was no change in tone.

I think my only option is to figure that G&L passive bass cut circuit out. I don't have caps that match (or are even close) for it and it looks like it uses a 1M pot and mine is 500K. I'll probably put this on hold for a while while.

I just took a circuits class... so maybe I can help a little. I don't know much about bass electronics yet, but I'm learning.

In a simple RC circuit - AC Voltage source, resistor and capacitor, if you measure the voltage across the capacitor, it behaves like a low pass filter. i.e. the voltage is the same as the voltage of the source for low frequencies, zero for extremely high frequencies. The opposite is true when measuring across the resistor - it behaves like a high pass filter, the voltage is the same at high frequencies but not at low ones.

So, if you switch the position of a resistor (the knob) and the capacitor, you should be able to get the effect you are talking about. I know that bass electronics are more complicated than an RC circuit, but I'm pretty sure the same concept applies here.

Ok, I tried this idea out today. Adjusting the pot had absolutely no effect on the sound. I tried taking the pot out of the circuit entirely and connected the hot wire from my pickup directly to one lead of the capacitor, the other capacitor lead I connected to the tip for the jack.

I expected the capacitor to work like a high pass filter. It did not. There was no difference in the sound with the capacitor or without it.

Anyone have any idea why?

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A capacitor by itself will cause no noticeable change in tone. It is the combination of capacitance with resistance that creates a tone control. The pot is the resistance that makes the tone control work.

A capacitor by itself will cause no noticeable change in tone. It is the combination of capacitance with resistance that creates a tone control. The pot is the resistance that makes the tone control work.

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That explains a lot. So do you have any idea how I would create a passive bass cut control?